Arctic plant origins and early formation of circumarctic distributions: a case study of the mountain sorrel, Oxyria digyna

Abstract

SummaryMany plant species comprising the present-day Arctic flora are thought to have originated in the high mountains of North America and Eurasia, migrated northwards as global temperatures fell during the late Tertiary period, and thereafter attained a circumarctic distribution. However, supporting evidence for this hypothesis that provides a temporal framework for the origin, spread and initial attainment of a circumarctic distribution by an arctic plant is currently lacking.Here we examined the origin and initial formation of a circumarctic distribution of the arctic mountain sorrel (Oxyria digyna) by conducting a phylogeographic analysis of plastid and nuclear gene DNA variation.We provide evidence for an origin of this species in the Qinghai-Tibet Plateau of southwestern China, followed by migration into Russia c. 11 million yr ago (Ma), eastwards into North America by c. 4 Ma, and westwards into Western Europe by c. 1.96 Ma. Thereafter, the species attained a circumarctic distribution by colonizing Greenland from both sides of the Atlantic Ocean.Following the arrival of the species in North America and Europe, population sizes appear to have increased and then stabilized there over the last 1 million yr. However, in Greenland a marked reduction followed by an expansion in population size is indicated to have occurred during the Pleistocene.

Late Pleistocene origin of the entire circumarctic range of the arctic‐alpine plant Kalmia procumbens

“…Recent phylogeographic studies of arctic‐alpine plant species have revealed that their genetic variation is typically highly structured due to several major geographic barriers that facilitated range separation (17 species, Eidesen et al., ; Silene acaulis , Gussarova et al., ). A few studies have estimated that major lineages within arctic‐alpine plants diverged prior to the middle Pleistocene ( Saxifraga oppositifolia , Abbott, ; Abbott & Comes, ; Vaccinium uliginosum , Alsos, Engelskjøn, Gielly, Taberlet, & Brochmann, ; Oxyria dygina , Wang et al., ), consistent with Hultén's () hypothesis of an early Pleistocene origin of their circumarctic ranges. However, several phylogeographic studies also suggest that some arctic‐alpine plants are capable of extensive long‐distance dispersal ( V. uliginosum , Alsos et al., ; Cassiope tetragona , Eidesen, Carlsen, Molau, & Brochmann, ; Saxifraga rivularis , Westergaard, Jørgensen, Gabrielsen, Alsos, & Brochmann, ), even from Alaska to southern South America ( Empetrum , Popp, Mirre, & Brochmann, ).…”

Species divergence and maintenance of species cohesion of three closely related Primula species in the Qinghai–Tibet Plateau

“…3–4 Ma at a time when global temperature decreased sharply (Matthews & Ovenden, ; Zachos, Pagani, Sloan, Thomas, & Billups, ). However, this study only focused on the QTP and further studies involving a finer sampling across the entirely distribution of P. nutans associated with large‐scale genomic data should be employed to gain a detailed knowledge of evolutionary history of this species (e.g., Wang et al., ).…”

Chasing ghosts: allopolyploid origin of Oxyria sinensis (Polygonaceae) from its only diploid congener and an unknown ancestor

“…These loci were previously surveyed in a study of populations of O. digyna (Table , Supporting information; Wang et al . ). DNA extractions and PCR amplifications, using homologous primers, were conducted following the procedures described by Wang et al .…”

“…We excluded from this analysis other O. digyna populations outside Asia because during and following colonization of these other regions, they might have been subject to mutation fixation rates and climatic oscillations different to those of Asian populations (Wang et al . ). The four demographic scenarios examined were (i) continuous population expansion since the origin of the two species, (ii) recent expansion, (iii) expansion–shrinkage and (iv) expansion–shrinkage–expansion.…”

“…) as implemented in R. A mutation rate of 1.2 × 10 −8 for nuclear sequences estimated from fossil calibration of Oxyria (Wang et al . ) was used for all time estimations in addition to the lowest and highest mutation rates recorded for plants, that is 1 × 10 −8 and 1.5 × 10 −8 (Ossowski et al . ; Holliday et al .…”